The present invention relates to a two-dimensional collimator module, an X-ray detector, an X-ray CT (Computed Tomography) apparatus, a method for assembling the two-dimensional collimator module, and a method for producing a two-dimensional collimator device.
In recent years, in an X-ray CT apparatus, the number of rows of X-ray detectors has increased so that the influence of scattered radiation in a slice direction has become serious. Accordingly, as a collimator for removing scattered radiation to be disposed on the X-ray incident surface side of each of the X-ray detectors, various two-dimensional collimators have been proposed in which a plurality of collimator plates are arranged not only in a channel direction, i.e., the direction of the fan angle of an X-ray, but also in the slice direction.
For example, a two-dimensional collimator has been proposed in which channel-direction collimator plates and slice-direction collimator plates are combined into a lattice-like configuration (see, e.g., Japanese Unexamined Patent Publication No. 2010-127630, FIGS. 1 to 7).
However, each of the two-dimensional collimators proposed so far is hard to assemble or machining therefor is difficult, and it is not easy to increase the positional accuracy thereof. For example, in the example of Japanese Unexamined Patent Publication No. 2010-127630, it is difficult to form slits by machining and, unless a groove width having a sufficient margin with respect to the plate thickness of the collimator in the slice direction is provided, it is difficult to insert, for example, several hundreds of slice-direction collimator plates into several tens of channel-direction collimator plates. However, if a sufficient margin is allowed for the groove width, the collimator plates incur a positional error or an inclination error.
Under such circumstances, a two-dimensional collimator module is in demand which allows the removal of scattered radiation in the channel direction and in the slice direction, is easy to assemble, and has high positional accuracy.